Fix 'Invited user can reject invite over federation several times' (#1341)

3 files changed, 18 insertions, 1 deletions

diff --git a/syncapi/storage/postgres/invites_table.go b/syncapi/storage/postgres/invites_table.go
index 530dc645..eed58c15 100644
--- a/syncapi/storage/postgres/invites_table.go
+++ b/syncapi/storage/postgres/invites_table.go
@@ -139,6 +139,14 @@ func (s *inviteEventsStatements) SelectInviteEventsInRange(
 			return nil, nil, err
 		}
 
+		// if we have seen this room before, it has a higher stream position and hence takes priority
+		// because the query is ORDER BY id DESC so drop them
+		_, isRetired := retired[roomID]
+		_, isInvited := result[roomID]
+		if isRetired || isInvited {
+			continue
+		}
+
 		var event gomatrixserverlib.HeaderedEvent
 		if err := json.Unmarshal(eventJSON, &event); err != nil {
 			return nil, nil, err
diff --git a/syncapi/storage/sqlite3/invites_table.go b/syncapi/storage/sqlite3/invites_table.go
index 45862efb..7da86683 100644
--- a/syncapi/storage/sqlite3/invites_table.go
+++ b/syncapi/storage/sqlite3/invites_table.go
@@ -150,6 +150,14 @@ func (s *inviteEventsStatements) SelectInviteEventsInRange(
 			return nil, nil, err
 		}
 
+		// if we have seen this room before, it has a higher stream position and hence takes priority
+		// because the query is ORDER BY id DESC so drop them
+		_, isRetired := retired[roomID]
+		_, isInvited := result[roomID]
+		if isRetired || isInvited {
+			continue
+		}
+
 		var event gomatrixserverlib.HeaderedEvent
 		if err := json.Unmarshal(eventJSON, &event); err != nil {
 			return nil, nil, err
diff --git a/syncapi/storage/tables/interface.go b/syncapi/storage/tables/interface.go
index 9d239d23..2ff229cb 100644
--- a/syncapi/storage/tables/interface.go
+++ b/syncapi/storage/tables/interface.go
@@ -33,7 +33,8 @@ type AccountData interface {
 type Invites interface {
 	InsertInviteEvent(ctx context.Context, txn *sql.Tx, inviteEvent gomatrixserverlib.HeaderedEvent) (streamPos types.StreamPosition, err error)
 	DeleteInviteEvent(ctx context.Context, inviteEventID string) (types.StreamPosition, error)
-	// SelectInviteEventsInRange returns a map of room ID to invite events.
+	// SelectInviteEventsInRange returns a map of room ID to invite events. If multiple invite/retired invites exist in the given range, return the latest value
+	// for the room.
 	SelectInviteEventsInRange(ctx context.Context, txn *sql.Tx, targetUserID string, r types.Range) (invites map[string]gomatrixserverlib.HeaderedEvent, retired map[string]gomatrixserverlib.HeaderedEvent, err error)
 	SelectMaxInviteID(ctx context.Context, txn *sql.Tx) (id int64, err error)
 }